1 Answer
1

The purpose of making a local apt repository is to use a given media as a resource for your packages, and this is one half.

After you have done this and updated apt with sudo apt-get update you can do an upgrade to a new release with

sudo apt-get dist-upgrade

But beware that this is not granted to work, if you can't solve a dependency you are likely to break your system, apt heavily relies on multiple repositories and online resources to solve all the dependencies.